Abstract. Stony soils that have a considerable amount of rock fragments are widespread around the world. However, experiments to determine effective hydraulic properties of stony soils (SHP), i.e. the water retention curve (WRC) and hydraulic conductivity curve (HCC), are challenging. Installation of measurement devices and sensors in these soils is difficult and the data are less reliable because of high local heterogeneity. Therefore, effective properties of stony soils especially in unsaturated hydraulic conditions are still not well understood. An alternative approach to evaluate the SHP of these systems with internal structural heterogeneity is numerical simulation. We used the Hydrus 2D/3D software to create virtual stony soils in 3D and simulate water flow for different volumetric rock fragment contents, f. Soils with volumetric stone contents from 11 to 37 % were created by placing impermeable spheres in the form of rock fragments in a sandy loam soil. Time series of local pressure heads in various depths, mean water contents and fluxes across the upper boundary were generated in a virtual evaporation experiment. Additionally, a multi-step unit gradient simulation was applied to determine effective values of hydraulic conductivity near saturation up to pF = 2. The generated data were evaluated by inverse modeling, assuming a homogeneous system, and the effective hydraulic properties were identified. The effective properties were compared with predictions from available scaling models of SHP for different volumes of rock fragments. Our results showed that scaling the WRC of the background soil based on only the value of f gives acceptable results in the case of impermeable rock fragments. However, the reduction of conductivity could not be simply scaled by the value of f. Predictions were highly improved by applying the Novák, Maxwell, and GEM models to scale the HCC. The Maxwell model matched the numerically identified HCC best.
{"title":"Effective hydraulic properties of 3D virtual stony soils identified by inverse modeling","authors":"M. Naseri, S. Iden, W. Durner","doi":"10.5194/soil-2021-99","DOIUrl":"https://doi.org/10.5194/soil-2021-99","url":null,"abstract":"Abstract. Stony soils that have a considerable amount of rock fragments are widespread around the world. However, experiments to determine effective hydraulic properties of stony soils (SHP), i.e. the water retention curve (WRC) and hydraulic conductivity curve (HCC), are challenging. Installation of measurement devices and sensors in these soils is difficult and the data are less reliable because of high local heterogeneity. Therefore, effective properties of stony soils especially in unsaturated hydraulic conditions are still not well understood. An alternative approach to evaluate the SHP of these systems with internal structural heterogeneity is numerical simulation. We used the Hydrus 2D/3D software to create virtual stony soils in 3D and simulate water flow for different volumetric rock fragment contents, f. Soils with volumetric stone contents from 11 to 37 % were created by placing impermeable spheres in the form of rock fragments in a sandy loam soil. Time series of local pressure heads in various depths, mean water contents and fluxes across the upper boundary were generated in a virtual evaporation experiment. Additionally, a multi-step unit gradient simulation was applied to determine effective values of hydraulic conductivity near saturation up to pF = 2. The generated data were evaluated by inverse modeling, assuming a homogeneous system, and the effective hydraulic properties were identified. The effective properties were compared with predictions from available scaling models of SHP for different volumes of rock fragments. Our results showed that scaling the WRC of the background soil based on only the value of f gives acceptable results in the case of impermeable rock fragments. However, the reduction of conductivity could not be simply scaled by the value of f. Predictions were highly improved by applying the Novák, Maxwell, and GEM models to scale the HCC. The Maxwell model matched the numerically identified HCC best.\u0000","PeriodicalId":22015,"journal":{"name":"Soil Science","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86971875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Santás-Miguel, Avelino Núñez-Delgado, E. Álvarez-Rodríguez, M. Díaz-Raviña, M. Arias-Estévez, D. Fernández-Calviño
Abstract. The widespread use of both heavy metals and antibiotics in livestock farming and their subsequent arrival on agricultural soils through manure/slurry spreading has become a problem of vital importance for human health and the environment. In the current research, a laboratory experiment was carried out for 42 days to study co-selection for tolerance of three tetracycline antibiotics (tetracycline, TC; oxytetracycline, OTC; chlortetracycline, CTC) in soils polluted with heavy metals (As, Cd, Zn, Cu, Ni, Cr and Pb) at high concentration levels (1000 mg kg−1 of each one, separately). Pollution Induced Community Tolerance (PICT) of the bacterial community was estimated using the leucine incorporation technique. The Log IC50 (logarithm of the concentration causing 50 % inhibition in bacterial community growth) values obtained in uncontaminated soil samples for all the heavy metals tested showed the following toxicity sequence: Cu > As > Cr ≥ Pb ≥ Cd > Zn > Ni. However, in polluted soil samples the toxicity sequence was: Cu > Pb ≥ As ≥ Cd ≥ Cr ≥ Ni ≥ Zn. Moreover, at high metal concentrations the bacterial communities show tolerance to the metal itself, this taking place for all the metals tested in the long term. The bacterial communities of the soil polluted with heavy metals showed also long-term co-tolerance to TC, OTC, and CTC. This kind of studies, focusing on the eventual increases of tolerance and co-tolerance of bacterial communities in agricultural soil, favored by the presence of other pollutants, is of crucial importance, mostly bearing in mind that the appearance of antibiotic resistance genes in soil bacteria could be transmitted to human pathogens.
摘要牲畜养殖中重金属和抗生素的广泛使用及其随后通过粪肥/泥浆扩散到农业土壤中，已成为对人类健康和环境至关重要的问题。本研究通过42天的室内实验，研究了三种四环素类抗生素(四环素、TC;氧四环素,场外交易;被重金属(As, Cd, Zn, Cu, Ni, Cr和Pb)污染的土壤中高浓度(分别为1000 mg kg - 1)的氯霉素(CTC)。利用亮氨酸掺入技术对细菌群落的污染诱导群落耐受性(PICT)进行了估算。未污染土壤样品中所有重金属对细菌群落生长抑制50%的浓度的对数IC50值显示:Cu > As > Cr≥Pb≥Cd > Zn > Ni。污染土壤样品的毒性顺序为Cu > Pb≥As≥Cd≥Cr≥Ni≥Zn。此外，在高金属浓度下，细菌群落表现出对金属本身的耐受性，这种情况长期发生在所有测试的金属上。重金属污染土壤的细菌群落也表现出对TC、OTC和CTC的长期共耐受性。这类研究的重点是在其他污染物的存在下，农业土壤中细菌群落的耐受性和共耐受性最终增加，这是至关重要的，主要考虑到土壤细菌中抗生素抗性基因的出现可能会传播给人类病原体。
{"title":"Tolerance of soil bacterial community to tetracycline antibiotics induced by As, Cd, Zn, Cu, Ni, Cr and Pb pollution","authors":"V. Santás-Miguel, Avelino Núñez-Delgado, E. Álvarez-Rodríguez, M. Díaz-Raviña, M. Arias-Estévez, D. Fernández-Calviño","doi":"10.5194/soil-2021-104","DOIUrl":"https://doi.org/10.5194/soil-2021-104","url":null,"abstract":"Abstract. The widespread use of both heavy metals and antibiotics in livestock farming and their subsequent arrival on agricultural soils through manure/slurry spreading has become a problem of vital importance for human health and the environment. In the current research, a laboratory experiment was carried out for 42 days to study co-selection for tolerance of three tetracycline antibiotics (tetracycline, TC; oxytetracycline, OTC; chlortetracycline, CTC) in soils polluted with heavy metals (As, Cd, Zn, Cu, Ni, Cr and Pb) at high concentration levels (1000 mg kg−1 of each one, separately). Pollution Induced Community Tolerance (PICT) of the bacterial community was estimated using the leucine incorporation technique. The Log IC50 (logarithm of the concentration causing 50 % inhibition in bacterial community growth) values obtained in uncontaminated soil samples for all the heavy metals tested showed the following toxicity sequence: Cu > As > Cr ≥ Pb ≥ Cd > Zn > Ni. However, in polluted soil samples the toxicity sequence was: Cu > Pb ≥ As ≥ Cd ≥ Cr ≥ Ni ≥ Zn. Moreover, at high metal concentrations the bacterial communities show tolerance to the metal itself, this taking place for all the metals tested in the long term. The bacterial communities of the soil polluted with heavy metals showed also long-term co-tolerance to TC, OTC, and CTC. This kind of studies, focusing on the eventual increases of tolerance and co-tolerance of bacterial communities in agricultural soil, favored by the presence of other pollutants, is of crucial importance, mostly bearing in mind that the appearance of antibiotic resistance genes in soil bacteria could be transmitted to human pathogens.\u0000","PeriodicalId":22015,"journal":{"name":"Soil Science","volume":"72 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90330853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Soil structure in terms of the spatial arrangement of pores and solid is highly relevant for most physical, biochemical processes in soil. While this is known for long a scientific approach to quantify soil structural characteristics was also missing for long. This was due to its buried nature but also due to the three-dimensional complexity. During the last two decades, tools to acquire full 3D images of undisturbed soil became more and more available and a number of powerful software tools were developed to reduce the complexity to a set of meaningful numbers. However, the standardization of soil structure analysis for a better comparability of the results is not well developed and the accessibility of required computing facilities and software is still limited. At this stage we introduce an open access Soil Structure Library (https://structurelib.ufz.de/) which offers well-defined soil structure analyses for X-ray CT data sets uploaded by interested scientists. At the same time, the aim of this library is to serve as an open data source for real pore structures as developed in a wide spectrum of different soil types under different site conditions all over the globe. By combining pore structure metrics with essential soil information requested during upload (e.g. bulk density, texture, organic carbon contentldots), this Soil Structure Library can be harnessed towards data mining and development of soil structure based pedotransfer functions. In this paper we describe the architecture of the Soil Structure Library and the provided metrics. This is complemented by an example how the data base can be used to address new research questions.
{"title":"An Open Soil Structure Library based on X-ray CT data","authors":"U. Weller, Lukas Albrecht, S. Schlüter, H. Vogel","doi":"10.5194/soil-2021-96","DOIUrl":"https://doi.org/10.5194/soil-2021-96","url":null,"abstract":"Abstract. Soil structure in terms of the spatial arrangement of pores and solid is highly relevant for most physical, biochemical processes in soil. While this is known for long a scientific approach to quantify soil structural characteristics was also missing for long. This was due to its buried nature but also due to the three-dimensional complexity. During the last two decades, tools to acquire full 3D images of undisturbed soil became more and more available and a number of powerful software tools were developed to reduce the complexity to a set of meaningful numbers. However, the standardization of soil structure analysis for a better comparability of the results is not well developed and the accessibility of required computing facilities and software is still limited. At this stage we introduce an open access Soil Structure Library (https://structurelib.ufz.de/) which offers well-defined soil structure analyses for X-ray CT data sets uploaded by interested scientists. At the same time, the aim of this library is to serve as an open data source for real pore structures as developed in a wide spectrum of different soil types under different site conditions all over the globe. By combining pore structure metrics with essential soil information requested during upload (e.g. bulk density, texture, organic carbon contentldots), this Soil Structure Library can be harnessed towards data mining and development of soil structure based pedotransfer functions. In this paper we describe the architecture of the Soil Structure Library and the provided metrics. This is complemented by an example how the data base can be used to address new research questions.\u0000","PeriodicalId":22015,"journal":{"name":"Soil Science","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91178236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-13DOI: 10.5194/soil-2021-79-supplement
Yuanyuan Yang, Zefang Shen, A. Bisset, R. V. Viscarra Rossel
Abstract. Soil fungi play important roles in the functioning of ecosystems, but they are challenging to measure. Using a continental scale dataset, we developed and evaluated a new method to estimate the relative abundance of the dominant phyla and diversity of fungi in Australian soil. The method relies on the development of spectro-transfer functions with state-of-the-art machine learning and using publicly available data on soil and environmental proxies for edaphic, climatic, biotic and topographic factors, and visible--near infrared (vis–NIR) wavelengths, to estimate the relative abundances of the Ascomycota, Basidiomycota, Glomeromycota, Mortierellomycota and Mucoromycota and community diversity measured with the abundance-based coverage estimator (ACE) index. The machine learning algorithms tested were partial least squares regression (PLSR), random forest (RF), Cubist, support vector machines (SVM), Gaussian process regression (GPR), XG-boost (XGB) and one-dimensional convolutional neural networks (1D-CNNs). The spectro-transfer functions were validated with a 10-fold cross-validation (n = 577). The 1D-CNNs outperformed the other algorithms and could explain between 45 and 73 % of fungal relative abundance and diversity. The models were interpretable, and showed that soil nutrients, pH, bulk density, an ecosystem water balance (a proxy for aridity) and net primary productivity were important predictors, as were specific vis–NIR wavelengths that correspond to organic functional groups, iron oxide and clay minerals. Estimates of the relative abundance for Mortierellomycota and Mucoromycota produced R2 ≥ 0.60, while estimates of the abundance of the Ascomycota and Basidiomycota produced R2 values of 0.5 and 0.58, respectively. The spectro-transfer functions for the Glomeromycota and diversity were the poorest with R2 values of 0.48 and 0.45, respectively. There is no doubt that the method provides estimates that are less accurate than more direct measurements with conventional molecular approaches. However, once the spectro-transfer functions are developed, they can be used with very little cost, and could serve to supplement the more expensive and laborious molecular approaches for a better understanding of soil fungal abundance and diversity under different agronomic and ecological settings.
{"title":"Supplementary material to \"Estimating soil fungal abundance and diversity at a macroecological scale with deep learning spectrotransfer functions\"","authors":"Yuanyuan Yang, Zefang Shen, A. Bisset, R. V. Viscarra Rossel","doi":"10.5194/soil-2021-79-supplement","DOIUrl":"https://doi.org/10.5194/soil-2021-79-supplement","url":null,"abstract":"Abstract. Soil fungi play important roles in the functioning of ecosystems, but they are challenging to measure. Using a continental scale dataset, we developed and evaluated a new method to estimate the relative abundance of the dominant phyla and diversity of fungi in Australian soil. The method relies on the development of spectro-transfer functions with state-of-the-art machine learning and using publicly available data on soil and environmental proxies for edaphic, climatic, biotic and topographic factors, and visible--near infrared (vis–NIR) wavelengths, to estimate the relative abundances of the Ascomycota, Basidiomycota, Glomeromycota, Mortierellomycota and Mucoromycota and community diversity measured with the abundance-based coverage estimator (ACE) index. The machine learning algorithms tested were partial least squares regression (PLSR), random forest (RF), Cubist, support vector machines (SVM), Gaussian process regression (GPR), XG-boost (XGB) and one-dimensional convolutional neural networks (1D-CNNs). The spectro-transfer functions were validated with a 10-fold cross-validation (n = 577). The 1D-CNNs outperformed the other algorithms and could explain between 45 and 73 % of fungal relative abundance and diversity. The models were interpretable, and showed that soil nutrients, pH, bulk density, an ecosystem water balance (a proxy for aridity) and net primary productivity were important predictors, as were specific vis–NIR wavelengths that correspond to organic functional groups, iron oxide and clay minerals. Estimates of the relative abundance for Mortierellomycota and Mucoromycota produced R2 ≥ 0.60, while estimates of the abundance of the Ascomycota and Basidiomycota produced R2 values of 0.5 and 0.58, respectively. The spectro-transfer functions for the Glomeromycota and diversity were the poorest with R2 values of 0.48 and 0.45, respectively. There is no doubt that the method provides estimates that are less accurate than more direct measurements with conventional molecular approaches. However, once the spectro-transfer functions are developed, they can be used with very little cost, and could serve to supplement the more expensive and laborious molecular approaches for a better understanding of soil fungal abundance and diversity under different agronomic and ecological settings.\u0000","PeriodicalId":22015,"journal":{"name":"Soil Science","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83473488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Kintl, V. Vlček, M. Brtnický, J. Nedělník, J. Elbl
Abstract. The presented research deals with the issue of the potential effect of adjuvants/wetting agents (WA) added to the spray mixture for stability of soil aggregates (SAS) in agricultural soil. Nine localities were chosen in the Czech Republic. Each locality was mapped using soil pits (depth min. 1.4 m). A total of 54 mixed samples were collected from the topsoil horizon in the selected localities. The samples were exposed to the action of four different types of wetting agents (organosilicone wetting agent; methyl ester of rapeseed oil; mixture of methyl ester palmitic and oleic acids; Isodecyl alcohol ethoxylate). SAS was determined before and after the addition of WA. Average values of SAS across the sampling point exhibited a demonstrable trend: the SAS value of control sample (without WA application) was at all times higher than in samples with the addition of WA (organosilicone wetting agent; mixture of methyl ester palmitic and oleic acids; Isodecyl alcohol ethoxylate), on average by more than 15 %. If the measured SAS values are compared in terms of overall means, it is obvious that the control variant always exhibited the highest SAS value (44.04 %) and the variants with the application of WA showed always SAS values lower by min. 16 %. All soil samples were also analysed for basic soil parameters (glomalin, Cox, pH, Na, P, Ca, K, Mg) in order to determine their potential influence on SAS and a possible elimination of the negative impact of WA. In this respect, only a significant influence of Cox content on SAS was recorded, which positively correlated with SAS.
{"title":"Potential effect of wetting agents added to agricultural sprays on the stability of soil aggregates","authors":"A. Kintl, V. Vlček, M. Brtnický, J. Nedělník, J. Elbl","doi":"10.5194/soil-2021-91","DOIUrl":"https://doi.org/10.5194/soil-2021-91","url":null,"abstract":"Abstract. The presented research deals with the issue of the potential effect of adjuvants/wetting agents (WA) added to the spray mixture for stability of soil aggregates (SAS) in agricultural soil. Nine localities were chosen in the Czech Republic. Each locality was mapped using soil pits (depth min. 1.4 m). A total of 54 mixed samples were collected from the topsoil horizon in the selected localities. The samples were exposed to the action of four different types of wetting agents (organosilicone wetting agent; methyl ester of rapeseed oil; mixture of methyl ester palmitic and oleic acids; Isodecyl alcohol ethoxylate). SAS was determined before and after the addition of WA. Average values of SAS across the sampling point exhibited a demonstrable trend: the SAS value of control sample (without WA application) was at all times higher than in samples with the addition of WA (organosilicone wetting agent; mixture of methyl ester palmitic and oleic acids; Isodecyl alcohol ethoxylate), on average by more than 15 %. If the measured SAS values are compared in terms of overall means, it is obvious that the control variant always exhibited the highest SAS value (44.04 %) and the variants with the application of WA showed always SAS values lower by min. 16 %. All soil samples were also analysed for basic soil parameters (glomalin, Cox, pH, Na, P, Ca, K, Mg) in order to determine their potential influence on SAS and a possible elimination of the negative impact of WA. In this respect, only a significant influence of Cox content on SAS was recorded, which positively correlated with SAS.\u0000","PeriodicalId":22015,"journal":{"name":"Soil Science","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88590802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhou Zijun, Zengqiang Li, C. Kun, Zhaoming Chen, Zeng Xiangzhong, Y. Hua, Song Guo, Shangguan Yuxian, Qing-rui Chen, H. Fan, S. Tu, Mingjiang He, Yu-sheng Qin
Abstract. Conservation tillage has attracted increasing attention over recent decades, mainly due to its benefits for improving soil organic matter content and reducing soil erosion. However, the effects of long-term straw mulching under a no-till system on soil physicochemical properties and bacterial communities at different soil depths are still unclear. In this 12-year experiment of straw removal (CK) and straw mulching (SM) treatments, soil samples were collected at 0–5, 5–10, 10–20, and 20–30 cm soil depths. The results showed that the contents of organic carbon (C), nitrogen (N), and phosphorus (P) fractions, and bacterial abundance significantly decreased, whereas pH significantly increased with soil depth. Compared with CK, SM significantly increased total N, inorganic N, available P, available potassium, and soil water content at 0–5 cm, total organic C content at 0–10 cm, and dissolved organic C and N contents at 0–20 cm. Regarding bacterial communities, SM increased the relative abundances of Proteobacteria, Bacteroidetes, and Acidobacteria but reduced those of Actinobacteria, Chloroflexi, and Cyanobacteria. Bacterial Shannon diversity and Shannon's evenness at 0–5 cm were reduced by SM treatment compared to CK treatment. Furthermore, SM increased the relative abundances of some C-cycling genera (such as Terracidiphilus and Acidibacter) and N-cycling genera (such as Rhodanobacter, Rhizomicrobium, Dokdonella, Reyranella, and Luteimonas) at 0–5 cm. Principal coordinate analysis showed that the largest difference in the composition of soil bacterial communities between CK and SM occurred at 0–5 cm. Soil pH and N and organic C fractions were the major drivers shaping soil bacterial communities. Overall, SM treatment is highly recommended under a no-till system because of its benefits to soil fertility and bacterial abundance.
{"title":"Changes in soil physicochemical properties and bacterial communities at different soil depths after long-term straw mulching under a no-till system","authors":"Zhou Zijun, Zengqiang Li, C. Kun, Zhaoming Chen, Zeng Xiangzhong, Y. Hua, Song Guo, Shangguan Yuxian, Qing-rui Chen, H. Fan, S. Tu, Mingjiang He, Yu-sheng Qin","doi":"10.5194/SOIL-7-595-2021","DOIUrl":"https://doi.org/10.5194/SOIL-7-595-2021","url":null,"abstract":"Abstract. Conservation tillage has attracted increasing attention\u0000over recent decades, mainly due to its benefits for improving soil organic\u0000matter content and reducing soil erosion. However, the effects of long-term\u0000straw mulching under a no-till system on soil physicochemical properties and\u0000bacterial communities at different soil depths are still unclear. In this\u000012-year experiment of straw removal (CK) and straw mulching (SM) treatments,\u0000soil samples were collected at 0–5, 5–10, 10–20, and 20–30 cm soil\u0000depths. The results showed that the contents of organic carbon (C), nitrogen\u0000(N), and phosphorus (P) fractions, and bacterial abundance significantly\u0000decreased, whereas pH significantly increased with soil depth. Compared with\u0000CK, SM significantly increased total N, inorganic N, available P, available\u0000potassium, and soil water content at 0–5 cm, total organic C content at\u00000–10 cm, and dissolved organic C and N contents at 0–20 cm. Regarding\u0000bacterial communities, SM increased the relative abundances of\u0000Proteobacteria, Bacteroidetes, and Acidobacteria but reduced those of\u0000Actinobacteria, Chloroflexi, and Cyanobacteria. Bacterial Shannon diversity\u0000and Shannon's evenness at 0–5 cm were reduced by SM treatment compared to\u0000CK treatment. Furthermore, SM increased the relative abundances of some\u0000C-cycling genera (such as Terracidiphilus and Acidibacter) and N-cycling genera (such as\u0000Rhodanobacter, Rhizomicrobium, Dokdonella, Reyranella, and Luteimonas) at 0–5 cm. Principal coordinate analysis showed that the\u0000largest difference in the composition of soil bacterial communities between\u0000CK and SM occurred at 0–5 cm. Soil pH and N and organic C fractions were\u0000the major drivers shaping soil bacterial communities. Overall, SM treatment\u0000is highly recommended under a no-till system because of its benefits to soil\u0000fertility and bacterial abundance.\u0000","PeriodicalId":22015,"journal":{"name":"Soil Science","volume":"61 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84898169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Merdy, Y. Lucas, B. Coulomb, A. Melfi, C. Montes
Abstract. Transfer of organic carbon from topsoil horizons to deeper horizons and to the water table is still little documented, in particular in equatorial environments, despite the high primary productivity of the evergreen forest. Due to its complexing capacity, organic carbon also plays a key role in the transfer of metals in the soil profile and, therefore, in pedogenesis and for metal mobility. Here we focus on equatorial podzols, which are known to play an important role in carbon cycling. We carried out soil column experiments using soil material and percolating solution sampled in an Amazonian podzol area in order to better constrain the conditions of the transfer of organic carbon at depth. The dissolved organic matter (DOM) produced in the topsoil was not able to percolate through the clayey, kaolinitic material from the deep horizons and was retained in it. When it previously percolated through the Bh material, there was production of fulvic-like, protein-like compounds and small carboxylic acids able to percolate through the clayey material and increase the mobility of Al, Fe and Si. Podzolic processes in the Bh can, therefore, produce a DOM likely to be transferred to the deep water table, playing a role in the carbon balances at the profile scale and, owing to its complexing capacity, playing a role in deep horizon pedogenesis and weathering. The order of magnitude of carbon concentration in the solution percolating at depth was around 1.5–2.5 mg L−1. Our findings reveal a fundamental mechanism that favors the formation of very thick kaolinitic saprolites.
{"title":"Soil organic carbon mobility in equatorial podzols: soil column experiments","authors":"P. Merdy, Y. Lucas, B. Coulomb, A. Melfi, C. Montes","doi":"10.5194/SOIL-7-585-2021","DOIUrl":"https://doi.org/10.5194/SOIL-7-585-2021","url":null,"abstract":"Abstract. Transfer of organic carbon from topsoil horizons to deeper horizons and to the water table is still little documented, in particular in equatorial environments, despite the high primary productivity of the evergreen forest. Due to its complexing capacity, organic carbon also plays a key role in the transfer of metals in the soil profile and, therefore, in pedogenesis and for metal mobility. Here we focus on equatorial podzols,\u0000which are known to play an important role in carbon cycling. We carried out\u0000soil column experiments using soil material and percolating solution sampled in an Amazonian podzol area in order to better constrain the conditions of the transfer of organic carbon at depth. The dissolved organic matter (DOM) produced in the topsoil was not able to percolate through the clayey, kaolinitic material from the deep horizons and was retained in it. When it previously percolated through the Bh material, there was production of fulvic-like, protein-like compounds and small carboxylic acids able to percolate through the clayey material and increase the mobility of Al, Fe and Si. Podzolic processes in the Bh can, therefore, produce a DOM likely to be transferred to the deep water table, playing a role in the carbon balances at the profile scale and, owing to its complexing capacity, playing a role in deep horizon pedogenesis and weathering. The order of magnitude of carbon concentration in the solution percolating at depth was around 1.5–2.5 mg L−1. Our findings reveal a fundamental mechanism that favors the formation of very thick kaolinitic saprolites.\u0000","PeriodicalId":22015,"journal":{"name":"Soil Science","volume":"133 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76718502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Soil degradation is a global challenge that is intrinsically linked to climate change and food security. Soil degradation has many causes, but all degraded soils suffer from poor soil structure. The UN’s Sustainable Development Goals 12, 13 and 15 strive towards responsible consumption and production, building a zero-waste circular economy, achieving net zero by 2030 and reversing land degradation to protect one of our most valuable assets, soil. Global efforts to stop and even reverse soil degradation require sources of both organic and inorganic materials to rebuild soil structure. The increasing global production of water treatment residual (WTR), an organo-mineral waste product from clean water treatment, means that the sustainable reuse of this waste provides a potential timely opportunity. Recycling or reuse of WTR to land is commonplace across the world but is subject to limitations based on the chemical properties of the material. Very little work has focused on the physical impacts of Fe-WTR application and its potential to rebuild soil structure particularly improving its ability to hold water and resist the effects of flooding. This paper presents novel research in which the use of Fe-WTR and Fe-WTR/compost [1:1] co-amendment has shown to be beneficial for a soil’s water retention, permeability, volume change, and strength properties. Application rates of WTR were 10 and 30 % by dry mass. Compared to the control soil, co-amended samples have 5.7 times the hydraulic conductivity (570 % improvement), 54 % higher shear strength and 25 % greater saturated water content. Single WTR amendment had 26 times the saturated hydraulic conductivity (2600 % improvement), 129 % higher shear strength and 13.7 % greater saturated water content. Data indicates that WTR can be added as a single amendment to significantly improve soil physical characteristics where shear strength and hydraulic conductivity are the most important factors in application. Although the co-application of Fe-WTR with compost provides a lesser improvement in shear strength and hydraulic conductivity compared to single WTR amendment, the co-amendment has the best water retention properties and provides supplementary organic content, which is beneficial for environmental applications where the soil health (i.e. ability to sustain ecosystem functions and support plants) is critical. We develop the term ‘flood holding capacity’ to holistically describe the physical ecosystem services that soil delivers, which incorporates not only the gravimetric water content but the extra water storage potential due to increases in volume that occur in organic rich soils, the transmissivity of the soil (hydraulic conductivity) and the shear strength of a soil, which determines how well a soil will resist the erosive forces of water movement.
{"title":"Reusing Fe water treatment residual as a soil amendment to improve physical function and flood resilience","authors":"Heather S. Kerr, K. Johnson, D. Toll","doi":"10.5194/soil-2021-94","DOIUrl":"https://doi.org/10.5194/soil-2021-94","url":null,"abstract":"Abstract. Soil degradation is a global challenge that is intrinsically linked to climate change and food security. Soil degradation has many causes, but all degraded soils suffer from poor soil structure. The UN’s Sustainable Development Goals 12, 13 and 15 strive towards responsible consumption and production, building a zero-waste circular economy, achieving net zero by 2030 and reversing land degradation to protect one of our most valuable assets, soil. Global efforts to stop and even reverse soil degradation require sources of both organic and inorganic materials to rebuild soil structure. The increasing global production of water treatment residual (WTR), an organo-mineral waste product from clean water treatment, means that the sustainable reuse of this waste provides a potential timely opportunity. Recycling or reuse of WTR to land is commonplace across the world but is subject to limitations based on the chemical properties of the material. Very little work has focused on the physical impacts of Fe-WTR application and its potential to rebuild soil structure particularly improving its ability to hold water and resist the effects of flooding. This paper presents novel research in which the use of Fe-WTR and Fe-WTR/compost [1:1] co-amendment has shown to be beneficial for a soil’s water retention, permeability, volume change, and strength properties. Application rates of WTR were 10 and 30 % by dry mass. Compared to the control soil, co-amended samples have 5.7 times the hydraulic conductivity (570 % improvement), 54 % higher shear strength and 25 % greater saturated water content. Single WTR amendment had 26 times the saturated hydraulic conductivity (2600 % improvement), 129 % higher shear strength and 13.7 % greater saturated water content. Data indicates that WTR can be added as a single amendment to significantly improve soil physical characteristics where shear strength and hydraulic conductivity are the most important factors in application. Although the co-application of Fe-WTR with compost provides a lesser improvement in shear strength and hydraulic conductivity compared to single WTR amendment, the co-amendment has the best water retention properties and provides supplementary organic content, which is beneficial for environmental applications where the soil health (i.e. ability to sustain ecosystem functions and support plants) is critical. We develop the term ‘flood holding capacity’ to holistically describe the physical ecosystem services that soil delivers, which incorporates not only the gravimetric water content but the extra water storage potential due to increases in volume that occur in organic rich soils, the transmissivity of the soil (hydraulic conductivity) and the shear strength of a soil, which determines how well a soil will resist the erosive forces of water movement.\u0000","PeriodicalId":22015,"journal":{"name":"Soil Science","volume":"81 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83874681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Philipp Baumann, Anatol Helfenstein, A. Gubler, A. Keller, R. Meuli, Daniel Wächter, Juhwan Lee, R. V. Viscarra Rossel, J. Six
Abstract. Information on soils' composition and physical, chemical and biological properties is paramount to elucidate agroecosystem functioning in space and over time. For this purpose, we developed a national Swiss soil spectral library (SSL; n=4374) in the mid-infrared (mid-IR), calibrating 16 properties from legacy measurements on soils from the Swiss Biodiversity Monitoring program (BDM; n=3778; 1094 sites) and the Swiss long-term Soil Monitoring Network (NABO; n=596; 71 sites). General models were trained with the interpretable rule-based learner CUBIST, testing combinations of {5,10,20,50, and 100} ensembles of rules (committees) and {2, 5, 7, and 9} nearest neighbors used for local averaging with repeated 10-fold cross-validation grouped by location. To evaluate the information in spectra to facilitate long-term soil monitoring at a plot level, we conducted 71 model transfers for the NABO sites to induce locally relevant information from the SSL, using the data-driven sample selection method RS-LOCAL. In total, 10 soil properties were estimated with discrimination capacity suitable for screening (R2≥0.72; ratio of performance to interquartile distance (RPIQ) ≥ 2.0), out of which total carbon (C), organic C (OC), total nitrogen (N), pH and clay showed accuracy eligible for accurate diagnostics (R2>0.8; RPIQ ≥ 3.0). CUBIST and the spectra estimated total C accurately with the root mean square error (RMSE) = 8.4 g kg−1 and the RPIQ = 4.3, while the measured range was 1–583 g kg−1 and OC with RMSE = 9.3 g kg−1 and RPIQ = 3.4 (measured range 0–583 g kg−1). Compared to the general statistical learning approach, the local transfer approach – using two respective training samples – on average reduced the RMSE of total C per site fourfold. We found that the selected SSL subsets were highly dissimilar compared to validation samples, in terms of both their spectral input space and the measured values. This suggests that data-driven selection with RS-LOCAL leverages chemical diversity in composition rather than similarity. Our results suggest that mid-IR soil estimates were sufficiently accurate to support many soil applications that require a large volume of input data, such as precision agriculture, soil C accounting and monitoring and digital soil mapping. This SSL can be updated continuously, for example, with samples from deeper profiles and organic soils, so that the measurement of key soil properties becomes even more accurate and efficient in the near future.
摘要关于土壤组成及其物理、化学和生物特性的信息对于阐明农业生态系统在空间和时间上的功能至关重要。为此，我们开发了瑞士国家土壤光谱库(SSL;n=4374)中红外(中红外)，校准来自瑞士生物多样性监测计划(BDM;n = 3778;1094个站点)和瑞士长期土壤监测网络(NABO;n = 596;71网站)。一般模型使用可解释的基于规则的学习器CUBIST进行训练，测试规则(委员会)的{5、10、20、50和100}集合和用于局部平均的{2、5、7和9}近邻的组合，并按位置分组进行重复的10倍交叉验证。为了评估光谱中的信息，以便在样地水平上进行长期土壤监测，我们使用数据驱动的样本选择方法RS-LOCAL，对NABO站点进行了71次模型转移，以从SSL中提取本地相关信息。共估计出10种土壤性质，具有适合筛选的判别能力(R2≥0.72;性能与四分位数间距比(RPIQ)≥2.0)，其中总碳(C)、有机碳(OC)、总氮(N)、pH和粘土的准确度符合准确诊断要求(R2>0.8;rpiq≥3.0)。CUBIST和光谱准确地估计了总C，均方根误差(RMSE) = 8.4 g kg - 1, RPIQ = 4.3，而测量范围为1 - 583 g kg - 1, OC的RMSE = 9.3 g kg - 1, RPIQ = 3.4(测量范围为0-583 g kg - 1)。与一般的统计学习方法相比，局部迁移方法-使用两个各自的训练样本-平均将每个站点的总C的RMSE降低了四倍。我们发现，与验证样本相比，所选择的SSL子集在光谱输入空间和测量值方面都非常不同。这表明数据驱动的RS-LOCAL选择利用化学成分的多样性而不是相似性。我们的研究结果表明，中红外土壤估计足够准确，可以支持许多需要大量输入数据的土壤应用，如精准农业、土壤C核算和监测以及数字土壤制图。这种SSL可以不断更新，例如，使用来自更深剖面和有机土壤的样本，以便在不久的将来对关键土壤特性的测量变得更加准确和高效。
{"title":"Developing the Swiss mid-infrared soil spectral library for local estimation and monitoring","authors":"Philipp Baumann, Anatol Helfenstein, A. Gubler, A. Keller, R. Meuli, Daniel Wächter, Juhwan Lee, R. V. Viscarra Rossel, J. Six","doi":"10.5194/soil-7-525-2021","DOIUrl":"https://doi.org/10.5194/soil-7-525-2021","url":null,"abstract":"Abstract. Information on soils' composition and physical, chemical and biological properties is paramount to elucidate agroecosystem functioning in space and over time. For this purpose, we developed a national Swiss soil spectral library (SSL; n=4374) in the mid-infrared (mid-IR), calibrating 16 properties from legacy measurements on soils from the Swiss Biodiversity Monitoring program (BDM; n=3778; 1094 sites) and the Swiss long-term Soil Monitoring Network (NABO; n=596; 71 sites). General models were trained with the interpretable rule-based learner CUBIST, testing combinations of {5,10,20,50, and 100} ensembles of rules (committees) and {2, 5, 7, and 9} nearest neighbors used for local averaging with repeated 10-fold cross-validation grouped by location. To evaluate the information in spectra to facilitate long-term soil monitoring at a plot level, we conducted 71 model transfers for the NABO sites to induce locally relevant information from the SSL, using the data-driven sample selection method RS-LOCAL. In total, 10 soil properties were estimated with discrimination capacity suitable for screening (R2≥0.72; ratio of performance to interquartile distance (RPIQ) ≥ 2.0), out of which total carbon (C), organic C (OC), total nitrogen (N), pH and clay showed accuracy eligible for accurate diagnostics (R2>0.8; RPIQ ≥ 3.0). CUBIST and the spectra estimated total C accurately with the root mean square error (RMSE) = 8.4 g kg−1 and the RPIQ = 4.3, while the measured range was 1–583 g kg−1 and OC with RMSE = 9.3 g kg−1 and RPIQ = 3.4 (measured range 0–583 g kg−1). Compared to the general statistical learning approach, the local transfer approach – using two respective training samples – on average reduced the RMSE of total C per site fourfold. We found that the selected SSL subsets were highly dissimilar compared to validation samples, in terms of both their spectral input space and the measured values. This suggests that data-driven selection with RS-LOCAL leverages chemical diversity in composition rather than similarity. Our results suggest that mid-IR soil estimates were sufficiently accurate to support many soil applications that require a large volume of input data, such as precision agriculture, soil C accounting and monitoring and digital soil mapping. This SSL can be updated continuously, for example, with samples from deeper profiles and organic soils, so that the measurement of key soil properties becomes even more accurate and efficient in the near future.\u0000","PeriodicalId":22015,"journal":{"name":"Soil Science","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88299999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. García-Gamero, T. Vanwalleghem, A. Peña, A. Román‐Sánchez, P. Finke
Abstract. The sensitivity of chemical weathering to climatic and erosional forcing is well established at regional scales. However, soil formation is known to vary strongly along catenas where topography, hydrology, and vegetation cause differences in soil properties and possibly chemical weathering. This study applies the SoilGen model to evaluate the link between topographic position and hydrology with the chemical weathering of soil profiles on a north-south catena in southern Spain. Pedogenesis was measured and simulated in seven selected locations over a 20000-year period. A good correspondence between simulated and measured chemical depletion fraction (CDF) was obtained (R2 = 0.47). An important variation in CDF values along the catena was observed, although the position along the catena alone, nor by the slope gradient, explained this variation well. However, the hydrological variables explained the observed trends better. A positive trend between CDF data and soil moisture and infiltration and a negative trend with water residence time was found. The model sensitivity was evaluated with a large precipitation gradient (200–1200 mm yr−1). While a marked depth gradient was obtained for CDF with precipitation up to 800 mm yr−1, a uniform depth distribution was obtained with precipitation above 800 mm yr−1. The basic pattern for the response of chemical weathering to precipitation is a unimodal curve, with a maximum around a mean annual precipitation value of 800 mm yr−1. Interestingly, this corroborates similar findings on the relation of other soil properties to precipitation and should be explored in further research.
摘要化学风化对气候和侵蚀强迫的敏感性在区域尺度上得到了很好的证实。然而，众所周知，土壤形成在地形、水文和植被导致土壤性质和可能的化学风化差异的链带上变化很大。本研究应用SoilGen模型来评估地形位置和水文之间的联系，以及西班牙南部南北连接线土壤剖面的化学风化。在2万年的时间里，在7个选定的地点测量和模拟了成土作用。模拟和测量的化学耗损分数(CDF)具有良好的对应关系(R2 = 0.47)。观察到CDF值沿链的重要变化，尽管沿链的位置单独，而不是斜坡梯度，很好地解释了这种变化。然而，水文变量更好地解释了观测到的趋势。CDF数据与土壤水分和入渗呈正相关，与水停留时间呈负相关。在大降水梯度(200-1200 mm yr - 1)下评估了模型的敏感性。当降水量达到800 mm yr - 1时，CDF的深度梯度明显，而当降水量超过800 mm yr - 1时，CDF的深度分布均匀。化学风化对降水响应的基本模式是单峰曲线，在年平均降水量800 mm yr−1附近有最大值。有趣的是，这证实了其他土壤性质与降水关系的类似发现，应该在进一步的研究中进行探索。
{"title":"Modelling the effect of catena position and hydrology on soil chemical weathering","authors":"V. García-Gamero, T. Vanwalleghem, A. Peña, A. Román‐Sánchez, P. Finke","doi":"10.5194/soil-2021-78","DOIUrl":"https://doi.org/10.5194/soil-2021-78","url":null,"abstract":"Abstract. The sensitivity of chemical weathering to climatic and erosional forcing is well established at regional scales. However, soil formation is known to vary strongly along catenas where topography, hydrology, and vegetation cause differences in soil properties and possibly chemical weathering. This study applies the SoilGen model to evaluate the link between topographic position and hydrology with the chemical weathering of soil profiles on a north-south catena in southern Spain. Pedogenesis was measured and simulated in seven selected locations over a 20000-year period. A good correspondence between simulated and measured chemical depletion fraction (CDF) was obtained (R2 = 0.47). An important variation in CDF values along the catena was observed, although the position along the catena alone, nor by the slope gradient, explained this variation well. However, the hydrological variables explained the observed trends better. A positive trend between CDF data and soil moisture and infiltration and a negative trend with water residence time was found. The model sensitivity was evaluated with a large precipitation gradient (200–1200 mm yr−1). While a marked depth gradient was obtained for CDF with precipitation up to 800 mm yr−1, a uniform depth distribution was obtained with precipitation above 800 mm yr−1. The basic pattern for the response of chemical weathering to precipitation is a unimodal curve, with a maximum around a mean annual precipitation value of 800 mm yr−1. Interestingly, this corroborates similar findings on the relation of other soil properties to precipitation and should be explored in further research.\u0000","PeriodicalId":22015,"journal":{"name":"Soil Science","volume":"84 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72497017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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